Safety device for refrigerating systems



29, 1936. 1 KlRGAN 2,055,543

SAFETY DEVICE FOR REFRIGERATING SYSTEMS Filed Dec. 19, 1934 INVENTOR.

Jog, [fir am. BY r CQ H15' ATTORNEY Patented Sept. 29, 1936 lPATENTOFFICE SAFETY DEVICE Fon REFRIGERATING sYsTEMs John Kirgan, Easton, Pa.,assignor to Ingersoll- Rand Company, Jersey City, N. J., a corporationof New Jersey Application December 19, 1934, Serial No. 758,182 3claims'. (01. 62-152) 'Ihis invention is an improvement in safetydevices, especially devices to insure the safe operation of machines inrefrigerating systems which act to chill a quantity of water to beafter- 5 wards used for cooling purposes.

In refrigeratingrsystems of this type, known as water-vapor refrigeratngapparatus, the cooling effect is brought about by converting a part ofthe water into vapor and lowering the temperalo ture of the main body ofthe water by the loss of heat which is extracted therefrom when saidvapor is formed. To this' end the water is intro-l duced into a -vesselor evaporator containing a high vacuum, and the Water vapor formed iswithl drawn by an evacuating member of sufficiently high capacity andtransferred to a condenser where it is liquefied. To remove the watervapor l from the evaporator a centrifugal compressor has been found tohave many advantages,` but such a compressor, to be of moderatedimensions and yet have the required capacity, must be operated at highspeed, andthe parts are therefore of comparativelylight construction.Hence it is important that nothing but water vapor be a1- 25 lowed toenter the housng of the compressor, be-

cause if water in liquid form is admitted and gets into the path of. thefast moving vanes thereof great damage such as the bending or breakingof the varies will ensue before this condition can be 3@ remedied.

` An object of my invention is to safe-guard the centrifugal compressorand prevent the admission thereto of water from the evaporator when thecompressor is running. 'I'his is accomplished I Y of water in liquidform to the compressor housing would begin, .and at once slow down andquicky ly stop the latter. Hence, even if some water 45 does enter thecompressor, the rapid diminution.

in the speed thereof will 'effectually prevent any harmful consequences.

With these and other objects and advantages in. view, the inventionconsists in the novel feao tures set forth in the description, andpointed out '1in the claims. But the disclosure is illustrative l onlyand changesmay be made without exceeding the scope and broad meanings ofthe terms in which the appended claims are expressed.

55 The drawing shows in outline a centrifugalv compressor water-vaporrefrigerating system with a safety device according to this invention.

The invention comprises an evaporator I to which the liquid refrigerant,such as water, is l admitted by way of pipe 2. This pipe comprises 5 asection which is disposed horizontally near the top of the evaporatorand is there provided with a number of openings to enable the water toissue therefrom in the form of sprays or jets. At the top of theevaporator is an outlet 3 leading into 10 the housing 4 of a centrifugalcompressor', which extracts water vapor from the evaporator and deliversit to a condenser (not shown) to be liquelied. This compressor is drivenby a motor such as an electric motor 5 connected to the rotor of 15 lthecompressor by step-up gearing indicated in outline by the numeral 6. Thecompressor may embrace several stages, each with a set of revolvingvanes on the compressor shaft operated by the motor 5'. To run themotor, electric current is supplied from mains 'I to suitableconnections including an overload switch or circuit-breaker 8. Therevolution of the rotor (not shown) in the compressor Il at`the start ofthe operation withdraws the .gaseous an/d vapor contents of theevaporator l and creates therein a vacuum so that when water is admittedby the pipe 2 and sprayed downwardly into the evaporator I, some ofl itis transformed into vapor at onceand this vapor is exhausted by thecompressor or rotary evacuator through the opening 3. The latent heat ofvaporization that is absorbed by the part of the water which isvaporized, will lower the tempera- Ature of the rest of the waterseveral degrees. The

main body of the water remains liquid and flows out through an outletopening Q in the bottom of the evaporator to a discharge pipe I0connected through a pump I I to a delivery conduit which is 4supply pipeor conduit 2 within the evaporator I is a valve I3 having an armextending outside of the pipe and controlled by a float lever I4,v Whenthe level of the water rises in the evaporator the float lever I4 tendsto close the valve I3, and to open this ,valve when the water levelsinks; Thus the admission of the Water is regulated. 50 Owing to thefact that the pressure in the evaporator I is quite low the chilledliquid which collects on the bottom of the evaporator must be forciblyremoved by the pump II. VSo long as the o pump Il continues working orthe valve I3 does^55 not get out of order, the water on the bottom oithe evaporator does not become very deep and there is no risk of any ofit reaching the top and passing through the outlet 3 into the housing 4of the compressor. If, however, the pump fails to Work or if the valveI3 gets out of order, the evaporator I may ll up with water, some ofwhich will then enter the compressor, and in the compressor housing therotating vanes of the compressor will collide with same. `To preventSuch an eventuality the top of the evaporator carries a pipe I5projecting downward into the evaporator, and carrying at its inner end-arelief valve l@ controlled by a oat arm I'I. Normally this iioat willnot be raised, but will hang in such a position as to close the valveIii. The upper or outer end of the pipe I5 opens through the bottom ofan outside receptacle I3 which is on the top of the evaporator andnormally contains enough water to form a seal for the valve I6. Thecompressor l will have water or other suitable liquid seals at 'thebearings of the drive shaft of the compressor,

so that the atmospheric air can not enter this housing around the driveshaft at its ends. Water or other liquid owing through these seals, orcoming Afrom any other source, can be Vdischarged by way of a pipe I9into the receptacle I8 and it is withdrawn from the receptacle I8 bypipe 2il. Hence the receptacle .I8 never overflows. f

With this construction if the evaporator I by any mischance ever llswith water, the float lll will be lifted to open the valve i6 before anyof the water can rise up to the compressor inlet 3, and as soon as thevalve I6 opens the water in the vessel I8 quickly drains into theevaporator and enough air is then admitted through the inlet passage inthe pipe I5 to destroyV the vacuum therein. The admission of air, whichis considerably heavier than water vapor, overloads the compressor, andthe speed of operation drops at once, so that even if the water in theevaporator rises and some of it gets into the compressor, no damage willresult. The overloading of the compresser and its motor causes theswitch to break the supply circuit of the motor, and then in a moment ortwo, the compressor entirely stops.

After the compressor ceases to run, Water might of course continue to bedischarged from the pipe 2 andrise in the evaporator I until it passesup through the outlet 3 into the compressor housing. As the vanes' arenow motionless, no ill eects will be produced, but before the system isagain started, the water level has to be lowered in the evaporator I andall the liquid cleared out of the compressor housing.

With this construction the system is safeguarded and all risk to themovable parts of the compressor is obviated. The arrangement is verysimple and adapted to work instantly to give the desired result Wheneveran emergency arises.

If the liquid ever gets high enough to open the valve I6, to admit air,overload of the motor occurs at once and the motor is cut out. Thedensity of the air acts as a brake and slows down the rotor of thecompressor to a speed which will not wreck or even damage the compressorshould Water enter the housing thereof.

I claimrvl. The combination of an evaporator having connections to admitand discharge a liquid refrigv erant. an evacuator to withdraw vapor ofthe reirigerant formed in the evaporatorfmeansfor supplying energy tooperate the evacuator, said means comprising a cut-oi device responsiveto overload, and means controlled by conditions in. the

iol

evaporator to bring about overloading of the evacuator and theenergy-supplying means to cause actuation of said cut-off device andthereby render the evacuator inoperative. A

2. The combination of an evaporator having connections to admit anddischarge a liquid refrigerant, means normally acting to maintainconstant refrigerant level in the evaporator, an evacuator to Withdrawvapor of the refrigerant formed in the evaporator, means for supplyingenergy to operate the evacuator, said meanscomprising a cut-0H deviceresponsive to overload, and means arranged to be actuated when therst-named means fails to operate to bring about overloading of theevacuator and the energy-supplying means and cause actuation of saidcut-oi device to stop the operation of the evacuator.

3. The combination of a chamber having a liquid inlet and outlet, afloat-actuated valve controlling the inlet and normally acting tomaintain the liquid in the chamber at constant level, an evacuatorcreating vacuum in the chamber and removing vapor therefrom, meansincluding a device responsive to overload and supplying energy toactuate the evacuator, normally-inoperative means arranged to operate atabnormally high liquid level in the chamber to admit a medium, heavierthan said vapor to the evacuator, the

medium upon admission acting to overload the evacuator and device to cutoi the supply of energy and render the evacuator inoperative, and meansproviding a liquid seal for the normally-inoperative means; i

. JOHN KIRGAN.

